Fix a problem in mod_proxy: it would not set the number of bytes

transferred, so other modules could not access the value from
the request_rec->bytes_sent field.
(And indeed, I also observed some time ago that the bytes_sent field was not set.)

PR: 6841
Submitted by:	Anthony Howe <achowe (at) snert.com>
Reviewed by:	Martin Kraemer


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@95362 13f79535-47bb-0310-9956-ffa450edef68